Engine combustion during vehicle operation may create vibration and/or oscillations that may be transmitted to the vehicle driver or that may cause degradation of other engine and/or vehicle components.
One approach to reduce such vibration, at least under some conditions, is to use a damper mounted to the crankshaft. In some cases, the damper may include a viscous fluid internal to the damper, along with an internal flywheel. Another type of damper can use elastomeric materials, such as described in U.S. Pat. No. 4,008,600. Such damper can then be tuned to reduce an amplitude of crankshaft fluctuations across a selected engine operating range.
The inventors herein have recognized that if degradation occurs to the damper (e.g., damping is reduced), then engine vibration may be increased beyond an acceptable level, causing customer dissatisfaction. Further, a reduction in damping may even cause engine or other component degradation. The inventors herein have also recognized that when using a viscous damper, degradation of the viscosity of the fluid may also cause a reduction in damping, and that such reduction may cause engine degradation.